Table 2.
| Hormone | Obesity | Proposed Pathophysiology in Obesity | Weight Loss/Fasting |
|---|---|---|---|
| Pituitary | |||
| Prolactin | |||
| Basal prolactin | N | N | |
| Prolactin response to hypoglycemia | N/↓ | N/↓ | |
| Prolactin response to TRH | N/↓ | N | |
| GH/IGF-I | |||
| GH | N/↓ | ↓↑ GHRH, ↑ GH-BP, ↑ insulin, ↓ ghrelin, ↑ somatostatin | ↑ |
| GH production rate | ↓ | ↑ | |
| GH metabolic rate | ↑ | ||
| GH response to GHRH | ↓ | N/↓ | |
| GH response to hypoglycemia | ↓ | N/↓ | |
| IGF-I | N/↓ | I ↑ GH sensitivity t ↑ intrahepatic triglyceride content |
|
| Free IGF-I | ↑ | ||
| IGFBP-3 | N/↑ | ||
| HPA axis in obesity | |||
| Basal cortisol (blood and salivary) | N | ↑↑ CRH, ↑ adipose 11-HSD, ↓ CBG Altered suppression tests due to hyperactivity of the HPA axis |
|
| Urinary free cortisol | N/↑ | ||
| Basal ACTH | N/↑ | ↑ CRH | |
| Cortisol production rate | ↑ | ||
| Cortisol metabolic rate | ↑ | ||
| 17-OH-corticosteroids | ↑ | ||
| HPA axis response to stimulatory tests in central obesity | |||
| Cortisol after CRH | ↑ | N | |
| ACTH after CRH | ↑ | ↑ | |
| Cortisol after tetracosactide | ↑ | ||
| Cortisol after hypoglycemia | ↑ | ||
| Thyroid | |||
| FT4 | N/slight ↓ | ↑↑ disposal | N |
| T3 | ↑ | Probably related to the amount of food intake and not to obesity itself. | ↓ |
| rT3 | ↓ | ↑ | |
| TSH | N/↑ | ↑↑ leptin and insulin ↑ peripheral T4 disposal |
N |
| TSH after TRH | N/↑/↓ | TRH dose decreases | |
| Parathyroid | |||
| PTH | N/↑ | Secondary due to vitamin D deficiency | |
| PTH ↑ calcium ↓ phosphate ↑ |
Pseudohypoparathyroidism Type 1a (Albright hereditary osteodystrophy) |
||
| Pancreas/Gut | |||
| Insulin | ↑ | Insulin resistance Insulinoma |
↓ with decreased insulin resistance |
| Ghrelin | ↓ | Lack of ghrelin decrease after meals | ↑ |
| GLP-1 | ↓ | ↑ FFA, microbiota | ↑ |
| Gonads | |||
| Testosterone (male) | ↓ | ↓ SHBG, ↑ aromatase, ↓ GnRH | ↑ testosterone and gonadotrophins, ↓ estradiol |
| Testosterone (female) | ↑ | Insulin resistance (PCOS) ↓ SHBG | ↓ serum total testosterone, androsterone and sulfate dehydroepiandrosterone (DHEA) |
| LH/FSH(male) | ↓ | ↑ oestrogens/androgens | ↑ SHBG, LH, and FSH |
| LH/FSH(female) | ↑ LH | Insulin resistance | ↑ Serum estradiol, FSH and SHBG |
| Adrenal | |||
| Renin | ↑ | ↑ Sympathetic tone | |
| Aldosterone | ↑ | ↑ Adipokines, renin- angiotensin, leptin | |
| Adipocyte | |||
| Leptin | ↑ | ↑ adipose mass, Leptin resistance | ↓ |
Abbreviations: 11-HSD, 11β-hydroxysteroid dehydrogenase; ACTH, adrenocorticotropic hormone; CBG, corticosteroid-binding globulin; CRH, corticotropin-releasing hormone; FFA, free fatty acids; FSH, follicle-stimulating hormone; FT4, free thyroxine; GH-BP, growth hormone-binding protein; GHRH, growth hormone-releasing hormone; GLP, glucagon-like peptide; GnRH, gonadotropin-releasing hormone; HPA, hypothalamic–pituitary–adrenal axis; IGF, insulin-like growth factor; LH, luteinizing hormone; PCOS, polycystic ovary syndrome; PTH, parathyroid hormone; SHBG, sex hormone-binding globulin; TSH, thyroid-stimulating hormone. ↑ Increase, ↓ decrease.